Nanoparticle-functionalized transition-metal carbides and nitrides (MXenes) have attracted extensive attention in electrochemical detection owing to their excellent catalytic performance. However, the mainstream synthetic routes rely on the batch method requiring strict experimental conditions, generally leading to low yield and poor size tunability of particles. Herein, we report a high-throughput and continuous microfluidic platform for preparing a functional MXene (Ti3C2Tx) with bimetallic nanoparticles (Pt-Pd NPs) at room temperature. Two 3D micromixers with helical elements were integrated into the microfluidic platform to enhance the secondary flow for promoting transport and reaction in the synthesis process. The rapid mixing and strong vortices in these 3D micromixers prevent aggregation of NPs in the synthesis process, enabling a homogeneous distribution of Pt-Pd NPs. In this study, Pt-Pd NPs loaded on the MXene nanosheets were synthesized under various hydrodynamic conditions of 1-15 mL min-1 with controlled sizes, densities, and compositions. The mean size of Pt-Pd NPs could be readily controlled within the range 2.4-9.3 nm with high production rates up to 13 mg min-1. In addition, synthetic and electrochemical parameters were separately optimized to improve the electrochemical performance of Ti3C2Tx/Pt-Pd. Finally, the optimized Ti3C2Tx/Pt-Pd was used for hydrogen peroxide (H2O2) detection and shows excellent electrocatalytic activity. The electrode modified with Ti3C2Tx/Pt-Pd here presents a wide detection range for H2O2 from 1 to 12 000 μM with a limit of detection down to 0.3 μM and a sensitivity up to 300 μA mM-1 cm-2, superior to those prepared in the traditional batch method. The proposed microfluidic approach could greatly enhance the electrochemical performance of Ti3C2Tx/Pt-Pd, and sheds new light on the large-scale production and catalytic application of the functional nanocomposites.
Keywords: MXenes; electrochemical detection; functional synthesis; microfluidics; nanoparticles.